The intestinal microbiota in health and disease: the influence of microbial products on immune cell homeostasis

Pesticides and the Gut Microbiota: Implications for Parkinson's Disease

Parkinson's disease (PD) affects more people worldwide than just aging alone can explain. This is likely due to environmental influences, genetic makeup, and changes in daily habits. The disease develops in a complex way, with movement problems caused by Lewy bodies and the loss of dopamine-producing neurons. Some research suggests Lewy bodies might start in the gut, hinting at a connection between these structures and gut health in PD patients. These patients often have different gut bacteria and metabolites. Pesticides are known to increase the risk of PD, with evidence showing they harm more than just dopamine neurons. Long-term exposure to pesticides in food might affect the gut barrier, gut bacteria, and the blood-brain barrier, but the exact link is still unknown. This review looks at how pesticides and gut bacteria separately influence PD development and progression, highlighting the harmful effects of pesticides and changes in gut bacteria. We have examined the interaction between pesticides and gut bacteria in PD patients, summarizing how pesticides cause imbalances in gut bacteria, the resulting changes, and their overall effects on the PD prognosis.

Metabolic immaturity of newborns and breast milk bile acid metabolites are the central determinants of heightened neonatal vulnerability to norovirus diarrhea

Noroviruses are the leading global cause of acute gastroenteritis, responsible for 685 million annual cases. While all age groups are susceptible to noroviruses, children are vulnerable to more severe infections than adults, underscored by 200 million pediatric cases and up to 200,000 deaths in children annually. Understanding the basis for the increased vulnerability of young hosts is critical to developing effective treatments. The pathogenic outcome of any enteric virus infection is governed by a complex interplay between the virus, intestinal microbiota, and host immune factors. A central mediator in these complex relationships are host- and microbiota-derived metabolites. Noroviruses bind a specific class of metabolites, bile acids, which are produced by the host and then modified by commensal bacterial enzymes. Paradoxically, bile acids can have both proviral and antiviral roles during norovirus infections. Considering these opposing effects, the microbiota-regulated balance of the bile acid pool may be a key determinant of the pathogenic outcome of a norovirus infection. The bile acid pool in newborns is unique due to immaturity of host metabolic pathways and developing gut microbiota, which could underlie the vulnerability of these hosts to severe norovirus infections. Supporting this concept, we demonstrate herein that microbiota and their bile acid metabolites protect from severe norovirus diarrhea whereas host-derived bile acids promote disease. Remarkably, we also report that maternal bile acid metabolism determines neonatal susceptibility to norovirus diarrhea during breastfeeding by delivering proviral bile acids to the newborn. Finally, directed targeting of maternal and neonatal bile acid metabolism can protect the neonatal host from norovirus disease. Altogether, these data support the conclusion that metabolic immaturity in newborns and ingestion of proviral maternal metabolites in breast milk are the central determinants of heightened neonatal vulnerability to norovirus disease.

A review on the antibiotic florfenicol: Occurrence, environmental fate, effects, and health risks

Florfenicol, as a replacement for chloramphenicol, can tightly bind to the A site of the 23S rRNA in the 50S subunit of the 70S ribosome, thereby inhibiting protein synthesis and bacterial proliferation. Due to the widespread use in aquaculture and veterinary medicine, florfenicol has been detected in the aquatic environment worldwide. Concerns over the effects and health risks of florfenicol on target and non-target organisms have been raised in recent years. Although the ecotoxicity of florfenicol has been widely reported in different species, no attempt has been made to review the current research progress of florfenicol toxicity, hormesis, and its health risks posed to biota. In this study, a comprehensive literature review was conducted to summarize the effects of florfenicol on various organisms including bacteria, algae, invertebrates, fishes, birds, and mammals. The generation of antibiotic resistant bacteria and spread antibiotic resistant genes, closely associated with hormesis, are pressing environmental health issues stemming from overuse or misuse of antibiotics including florfenicol. Exposure to florfenicol at μg/L-mg/L induced hormetic effects in several algal species, and chromoplasts might serve as a target for florfenicol-induced effects; however, the underlying molecular mechanisms are completely lacking. Exposure to high levels (mg/L) of florfenicol modified the xenobiotic metabolism, antioxidant systems, and energy metabolism, resulting in hepatotoxicity, renal toxicity, immunotoxicity, developmental toxicity, reproductive toxicity, obesogenic effects, and hormesis in different animal species. Mitochondria and the associated energy metabolism are suggested to be the primary targets for florfenicol toxicity in animals, albeit further in-depth investigations are warranted for revealing the long-term effects (e.g., whole-life-cycle impacts, multigenerational effects) of florfenicol, especially at environmental levels, and the underlying mechanisms. This will facilitate the evaluation of potential hormetic effects and construction of adverse outcome pathways for environmental risk assessment and regulation of florfenicol.

Parkinson's disease and gut microbiota: from clinical to mechanistic and therapeutic studies

Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases. The typical symptomatology of PD includes motor symptoms; however, a range of nonmotor symptoms, such as intestinal issues, usually occur before the motor symptoms. Various microorganisms inhabiting the gastrointestinal tract can profoundly influence the physiopathology of the central nervous system through neurological, endocrine, and immune system pathways involved in the microbiota-gut-brain axis. In addition, extensive evidence suggests that the gut microbiota is strongly associated with PD. This review summarizes the latest findings on microbial changes in PD and their clinical relevance, describes the underlying mechanisms through which intestinal bacteria may mediate PD, and discusses the correlations between gut microbes and anti-PD drugs. In addition, this review outlines the status of research on microbial therapies for PD and the future directions of PD-gut microbiota research.

Effects of Glycyrrhiza Polysaccharides on Chickens' Intestinal Health and Homeostasis

The overuse of antibiotics in poultry farming causes the accumulation of drug residue in animals' bodies and the occurrence of antibiotic-resistant bacteria, which not only compromise animals' health but ultimately endanger human health. Thus, there is an urgent need for a novel poultry feed additive to substitute for excessive antibiotics. Glycyrrhiza polysaccharides (GPS) derived from Chinese licorice have shown promising immunomodulatory effects in previous studies. The present study investigated the pharmacological effects of GPS on poultry intestines to assess whether it can be used as a feed additive. The results show that GPS can increase production of sIgA, promote the secretion activity of goblet cells, alter the gut microbial composition and lead to changes in short-chain fatty acids. GPS also elevated both Th1 and Th2 immune responses by facilitating the expression of IL-2, IL-4, IL-1β, and IFN-γ while increasing the proportion of both CD4+ and CD8+ cells in the intestine. Moreover, the results of 16S rRNA gene sequencing showed that GPS could significantly change intestinal microbiota composition in the intestine, evidenced by the increased proportion of Bacteroides, Butyricicoccus and Eisenbergiella, as well as a decreased portion of Erysipelatoclostridium, leading to a healthier intestinal microbiota composition for the host. Taken together, it can be concluded that GPS is safe to use as a novel feed additive that can be used as an alternative to prophylactic antibiotics in poultry feeding.

How Does Epstein–Barr Virus Interact With Other Microbiomes in EBV-Driven Cancers?

The commensal microbiome refers to a large spectrum of microorganisms which mainly consists of viruses and bacteria, as well as some other components such as protozoa and fungi. Epstein–Barr virus (EBV) is considered as a common component of the human commensal microbiome due to its spread worldwide in about 95% of the adult population. As the first oncogenic virus recognized in human, numerous studies have reported the involvement of other components of the commensal microbiome in the increasing incidence of EBV-driven cancers. Additionally, recent advances have also defined the involvement of host–microbiota interactions in the regulation of the host immune system in EBV-driven cancers as well as other circumstances. The regulation of the host immune system by the commensal microbiome coinfects with EBV could be the implications for how we understand the persistence and reactivation of EBV, as well as the progression of EBV-associated cancers, since majority of the EBV persist as asymptomatic carrier. In this review, we attempt to summarize the possible mechanisms for EBV latency, reactivation, and EBV-driven tumorigenesis, as well as casting light on the role of other components of the microbiome in EBV infection and reactivation. Besides, whether novel microbiome targeting strategies could be applied for curing of EBV-driven cancer is discussed as well.

Cultivating human tissues and organs over lab-on-a-chip models: Recent progress and applications

In vivo models are indispensable for preclinical studies for various human disease modeling and drug screening, however, face several obstacles such as animal model species differences and ethical clearance. Additionally, it is difficult to accurately predict the organ interaction, drug efficacy, and toxicity using conventional in vitro two-dimensional (2D) cell culture models. The microfluidic-based systems provide excellent opportunity to recapitulate the human organ/tissue functions under in vitro conditions. The organ/tissue-on-chip models are one of best emerging technologies that offer functional organs/tissues on a microfluidic chip. This technology has potential to noninvasively study the organ physiology, tissue development, and diseases etymology. This chapter comprises the benifits of 2D and three-dimensional (3D) in vitro cultures as well as highlights the importance of microfluidic-based lab-on-a-chip technique. The development of different organs/tissues-on-chip models and their biomedical application in various diseases such as cardiovascular diseases, neurodegenerative diseases, respiratory-based diseases, cancers, liver and kidney diseases, etc., have also been discussed.

Risk Factors for Childhood Leukemia: Radiation and Beyond

Childhood leukemia (CL) is undoubtedly caused by a multifactorial process with genetic as well as environmental factors playing a role. But in spite of several efforts in a variety of scientific fields, the causes of the disease and the interplay of possible risk factors are still poorly understood. To push forward the research on the causes of CL, the German Federal Office for Radiation Protection has been organizing recurring international workshops since 2008 every two to three years. In November 2019 the 6th International Workshop on the Causes of CL was held in Freising and brought together experts from diverse disciplines. The workshop was divided into two main parts focusing on genetic and environmental risk factors, respectively. Two additional special sessions addressed the influence of natural background radiation on the risk of CL and the progress in the development of mouse models used for experimental studies on acute lymphoblastic leukemia, the most common form of leukemia worldwide. The workshop presentations highlighted the role of infections as environmental risk factor for CL, specifically for acute lymphoblastic leukemia. Major support comes from two mouse models, the Pax5+/- and Sca1-ETV6-RUNX1 mouse model, one of the major achievements made in the last years. Mice of both predisposed models only develop leukemia when exposed to common infections. These results emphasize the impact of gene-environment-interactions on the development of CL and warrant further investigation of such interactions - especially because genetic predisposition is detected with increasing frequency in CL. This article summarizes the workshop presentations and discusses the results in the context of the international literature.

Lactic Acid Bacteria - A Promising Tool for Controlling Chicken Campylobacter Infection

Since 2005, campylobacteriosis has been the most common zoonotic disease in Europe. The main reservoir of pathogenic Campylobacter strains is broilers, which makes raw and undercooked poultry meat two major sources of disease. Infection in chicken flocks is most often asymptomatic, despite a high level of colonization reaching 106-109cfu/g in animal ceca. It is widely believed that controlling the level of colonization of the birds' digestive tract by pathogenic strains is a good way to increase food safety. Many treatments have been proposed to combat or at least reduce the level of colonization in animals reservoirs: probiotics, bacteriophages, vaccines, and anti-Campylobacter bacteriocins. This review focuses on the effects of Campylobacter infection on the chicken microbiome and colonization control strategies using probiotics (mostly lactic acid bacteria, LAB), which are live microorganisms included in the diet of animals as feed additives or supplements. Probiotics are not only an alternative to antibiotics, which were used for years as animal growth promoters, but they also constitute an effective protective barrier against excessive colonization of the digestive system by pathogenic bacteria, including Campylobacter. Moreover, one of the many beneficial functions of probiotics is the ability to manipulate the host's microbiota. Recently, there have also been some promising attempts to use lactic acid bacteria as a delivery system of oral vaccine against Campylobacter. Recombinant LAB strains induce primarily a mucosal immune response against foreign antigens, accompanied by at most a low-level immune response against carrier strains. Since the main barrier against the invasion of pathogens in the gastrointestinal tract is the intestinal mucosal membrane, the development of effective oral vaccines to protect animals against enteric infection is very reasonable.

Alteration of the gut microbiota in post-weaned calves following recovery from bovine coronavirus-mediated diarrhea

Bovine coronavirus (BCoV) is associated with severe diarrhea, dehydration, and depression, which result in significant economic damages in the dairy and beef cattle industries worldwide. However, differences in the gut microbiota structure and their correlations with differing physiological parameters between BCoV-infected calves with diarrhea and recovered calves are not well understood. In this study, fecal specimens were collected from 10 post-weaned calves, before and after 2 months of fluid therapy, and the samples were used for microbiota analysis. Following recovery, the alpha-diversity profiles (observed operational taxonomic units [OTUs], and Chao1, Shannon, and Simpson indices) changed significantly when compared with those of calves with diarrhea. Beta-diversity analysis exhibited significant differences in gut microbiota compositions between calves with diarrhea and those in the recovered state. The abundances of eight phyla and thirteen genera in feces changed markedly after restoration of BCoV diarrhea. In addition, our correlation study clearly revealed that increased abundances of the genera Caproiciproducens, Pseudoflavonifractor, and Oscillibacter negatively correlated with serum glucose, and phosphorus levels, but positively correlated with serum chloride in calves with diarrhea, whereas increased abundances of the genera Peptostreptococcaceae;Clostridium (Clostridium cluster XI), Intestinibacter, Cellulosilyticum, Ruminococcus, Romboutsia, Paeniclostridium, Clostridiaceae;Clostridium and Turicibacter in recovered calves showed the opposite pattern. These results suggest that structural changes of the gut microbiota after recovery from BCoV infection correlate with changes in physiological parameters. In conclusion, our data provide evidence of gut microbiota-composition changes and their correlations with the physical profiles of post-weaned calves, before and after fluid therapy for BCoV-related diarrhea.

Effects of Lactobacillus plantarum Q180 on Postprandial Lipid Levels and Intestinal Environment: A Double-Blind, Randomized, Placebo-Controlled, Parallel Trial

Probiotics can improve the intestinal environment by enhancing beneficial bacteria to potentially regulate lipid levels; however, the underlying mechanisms remain unclear. The aim of this study was to investigate the effect of Lactobacillus plantarum Q180 (LPQ180) on postprandial lipid metabolism and the intestinal microbiome environment from a clinical perspective. A double-blind, randomized, placebo-controlled study was conducted including 70 participants of both sexes, 20 years of age and older, with healthy blood triacylglyceride (TG) levels below 200 mg/dL. Treatment with LPQ180 for 12 weeks significantly decreased LDL-cholesterol (p = 0.042) and apolipoprotein (Apo)B-100 (p = 0.003) levels, and decreased postprandial maximum concentrations (C_max) and areas under the curve (AUC) of TG, chylomicron TG, ApoB-48, and ApoB-100. LPQ180 treatment significantly decreased total indole and phenol levels (p = 0.019). In addition, there was a negative correlation between baseline microbiota abundance and lipid marker change, which was negatively correlated with metabolites. This study suggests that LPQ180 might be developed as a functional ingredient to help maintain healthy postprandial lipid levels through modulating gut environment.

A long-distance relationship: the commensal gut microbiota and systemic viruses

Recent advances defining the role of the commensal gut microbiota in the development, education, induction, function, and maintenance of the mammalian immune system inform our understanding of how immune responses govern the outcome of systemic virus infection. While characterization of the impact of the local oral, respiratory, dermal and genitourinary microbiota on host immune responses and systemic virus infection is in its infancy, the gut microbiota interacts with host immunity systemically and at distal non-gastrointestinal tract sites to modulate the pathogenesis of systemic viruses. Gut microbes, microbe-associated molecular patterns, and microbe-derived metabolites engage receptors expressed on the cell surface, in the endosome, or in the cytoplasm to orchestrate optimal innate and adaptive immune responses important for controlling systemic virus infection.

The role of the gut microbiome in sex differences in arterial pressure

There has been intense interest in the role of the gut microbiome in human health and a broad range of diseases in recent years. In the context of cardiovascular disease, gut dysbiosis (defined as a change in the gut microbiome and the gut-epithelial barrier) has been linked to disturbances in blood pressure (BP) regulation. These findings build upon our understanding of the complex pathophysiology of essential hypertension. There are clear sex differences in the epidemiology of hypertension, with distinct trends in BP across the life-course in men and women. To date, a role for the gut microbiome in contributing to the sex differences in BP is yet to be clearly established. The purpose of this review is to summarise the current literature regarding how the gut microbiome differs between men and women and to investigate whether sex-determined differences in the gut microbiome influence the response to factors such as diet, obesity and inflammation. Finally, we will explore evidence for the possible interaction between sex-specific factors, including sex hormones and pregnancy, with the gut in the context of hypertension pathophysiology.

Obesidade: uma abordagem inflamatória e microbiana

A obesidade está intimamente ligada ao estado inflamatório, sendo considerada uma patologia metabólica complexa. Dietas hipercalóricas alteram a composição da microbiota intestinal, sendo a mudança da proporção de bactérias dos filos Bacteroidetes e Firmicutes uma das consequências mais conhecidas.  Essa mudança determina a produção de metabólitos específicos do sistema imune, induzindo estado inflamatório responsável pelo agravamento de uma série de doenças. A dieta hipercalórica representa um fator de risco para a obesidade e para o diabetes mellitus, doenças interligadas pelo conceito de lipotoxicidade, e o estado inflamatório também contribui para o aparecimento e para a progressão de doenças cardiovasculares. Com esse artigo, objetivamos estudar a obesidade pela perspectiva imunológica e microbiológica, abordando as consequências de dietas hipercalóricas sobre o estado inflamatório e a sobre a microbiota. Ademais, associar a mudança no microbioma a doenças prevalentes como o diabetes mellitus e as doenças cardiovasculares, apontando abordagens terapêuticas potenciais.

Impact of violacein from Chromobacterium violaceum on the mammalian gut microbiome

Violacein is a violet pigment produced by Chromobacterium violaceum that possesses several functions such as antibacterial, antiviral, antifungal, and antioxidant activities. The search for potential compounds and therapies that may interfere with and modulate the gut microbial consortia without causing severe damage and increased resistance is important for the treatment of inflammatory, allergic, and metabolic diseases. The aim of the present work was to evaluate the ability of violacein to change microbial patterns in the mammalian gut by favoring certain groups over the others in order to be used as a therapy for diseases associated with changes in the intestinal microflora. To do this, we used male Wistar rats, and administered violacein orally, in low (50 μg/ml) and high (500 μg/ml) doses for a month. Initially, the changes in the microbial diversity were observed by DGGE analyses that showed that the violacein significantly affects the gut microbiota of the rats. Pyrosequencing of 16S rDNA was then employed using a 454 GS Titanium platform, and the results demonstrated that higher taxonomic richness was observed with the low violacein treatment group, followed by the control group and high violacein treatment group. Modulation of the microbiota at the class level was observed in the low violacein dose, where Bacilli and Clostridia (Firmicutes) were found as dominant. For the high violacein dose, Bacilli followed by Clostridia and Actinobacteria were present as the major components. Further analyses are crucial for a better understanding of how violacein affects the gut microbiome and whether this change would be beneficial to the host, providing a framework for the development of alternative treatment strategies for intestinal diseases using this compound.

Communication Between the Microbiota and Mammalian Immunity

Mammalian immune systems evolved within a diverse world dominated by microbes, making interactions between these two life-forms inevitable. Adaptive immunity protects against microbes through antigen-specific responses. In classical studies, these responses were investigated in the context of pathogenicity; however, we now know that they have significant effects on our resident microbes. In turn, microbes employ an arsenal of mechanisms to influence development and specificity of host immunity. Understanding these complex reactions will be necessary to develop microbiota-based strategies to prevent or treat disease. Here we review the literature detailing the cross talk between resident microbes with a focus on the specificity of host responses and the microbial molecules that influence them.

Relevance of placental type I interferon beta regulation for pregnancy success

Pregnancy is a unique immunologic and microbial condition that requires an adequate level of awareness to provide a fast and protective response against pathogens as well as to maintain a state of tolerance to paternal antigens. Dysregulation of inflammatory pathways in the placenta triggered by pathogens is one of the main factors responsible for pregnancy complications. Type I IFNs are key molecules modulating immune responses at the level of the placenta and are crucial for protection of the pregnancy via their antiviral and immune modulatory properties. In this study, we elucidate the mechanisms controlling the basal expression of IFNβ and its negative feedback. Using in vitro and in vivo animal models, we found that TLR signaling maintains basal IFNβ levels through the TLR4-MyD88-independent TBK/IRF3 signaling pathway. We describe the role of the TAM receptor Axl in the regulation of IFNβ function in human and mouse trophoblast cells. The absence of TAM receptors in vivo is associated with fetal demise due to dysregulation of IFNβ expression and its pro-apoptotic downstream effectors. Collectively, our data describe a feedback signaling pathway controlling the expression and function of IFNβ in the trophoblast that is essential for an effective response during viral and microbial infections.

Genetic and Imaging Approaches Reveal Pro-Inflammatory and Immunoregulatory Roles of Mast Cells in Contact Hypersensitivity

Contact hypersensitivity (CHS) is a common T cell-mediated skin disease induced by epicutaneous sensitization to haptens. Mast cells (MCs) are widely deployed in the skin and can be activated during CHS responses to secrete diverse products, including some with pro-inflammatory and anti-inflammatory functions. Conflicting results have been obtained regarding pathogenic versus protective roles of MCs in CHS, and this has been attributed in part to the limitations of certain models for studying MC functions in vivo. This review discusses recent advances in the development and analysis of mouse models to investigate the roles of MCs and MC-associated products in vivo. Notably, fluorescent avidin-based two-photon imaging approaches enable in vivo selective labeling and simultaneous tracking of MC secretory granules (e.g., during MC degranulation) and MC gene activation by real-time longitudinal intravital microscopy in living mice. The combination of such genetic and imaging tools has shed new light on the controversial role played by MCs in mouse models of CHS. On the one hand, they can amplify CHS responses of mild severity while, on the other hand, can limit the inflammation and tissue injury associated with more severe or chronic models, in part by representing an initial source of the anti-inflammatory cytokine IL-10.

The Microbiota, the Gut and the Brain in Eating and Alcohol Use Disorders: A 'Ménage à Trois'?

Aims

Accumulating evidence for the influence of the gut microbiota on the bidirectional communication along the gut-brain axis suggests a role of the gut microbiota in eating disorders (EDs) and alcohol and substance use disorders. The potential influence of altered gut microbiota (dysbiosis) on behaviors associated with such disorders may have implications for developing therapeutic interventions.

Methods

A systematic review of preclinical and clinical studies evaluating the gut microbiota, EDs and alcohol and substance use disorders was conducted using MEDLINE, Embase and Web of Science databases with the objective being to examine the role of the gut microbiota in behavioral correlates of these disorders. Original papers focused on the gut microbiota and potential behavioral implications were deemed eligible for consideration.

Results

The resulting 12 publications were limited to gut microbiota studies related to EDs and alcohol and substance use disorders. Some studies suggest that dysbiosis and gut microbial byproducts may influence the pathophysiology of EDs via direct and indirect interference with peptide hormone signaling. Additionally, dysbiosis was shown to be correlated with alcohol use disorder-related symptoms, i.e. craving, depression and anxiety. Finally, a mouse study suggests that manipulations in the gut microbiota may affect cocaine-related behaviors.

Conclusions

Promising, albeit preliminary, findings suggest a potential role of the gut microbiota in behavioral correlates of EDs and alcohol and substance use disorders.

Short summary

Preliminary evidence exists supporting the role of the gut microbiota in eating disorders and alcohol and substance use disorders, although additional investigation is needed to determine what is causative versus epiphenomenological.

Targeting gut microbiota in hepatocellular carcinoma: probiotics as a novel therapy

Hepatocellular carcinoma (HCC), the most common primary liver cancer, is one of the dreaded complications of chronic liver disease. Recent experimental and clinical studies have revealed that the alteration of gut-liver axis plays a pivotal role in the onset of chronic liver diseases, including HCC. Altered gut microbiota and endotoxemia are increasingly recognized as critical components in promoting the progression of chronic liver diseases to HCC. Probiotics have been suggested as a novel, safe and cost-effective approach to prevent or treat HCC. Mechanisms by which probiotics exerts their anti-cancer effects include their ability to bind carcinogens, modulation of gut microbiota, improvement of intestinal barrier function, and immunomodulation. This review summarizes the literature findings of the changes in gut microbiota linked to HCC, and discusses the possible therapeutic implications of probiotics for HCC.

Bacterial infections and hepatic encephalopathy in liver cirrhosis-prophylaxis and treatment

Infections are common among patients with liver cirrhosis. They occur more often in cirrhotic patient groups than in the general population and result in higher mortality. One reason for this phenomenon is bacterial translocation from the intestinal lumen that occurs as a consequence of intestinal bacterial overgrowth, increased permeability and decreased motility. The most common infections in cirrhotic patients are spontaneous bacterial peritonitis and urinary tract infections, followed by pneumonia, skin and soft tissue infections. Intestinal bacterial overgrowth is also responsible for hyperammonemia, which leads to hepatic encephalopathy. All of these complications make this group of patients at high risk for mortality. The role of antibiotics in liver cirrhosis is to treat and in some cases to prevent the development of infectious complications. Based on our current knowledge, antibiotic prophylaxis should be administered to patients with gastrointestinal hemorrhage, low ascitic fluid protein concentration combined with liver or renal failure, and spontaneous bacterial peritonitis as a secondary prophylaxis, as well as after hepatic encephalopathy episodes (also as a secondary prophylaxis). In some cases, the use of non-antibiotic prophylaxis can also be considered. Current knowledge of the treatment of infections allows the choice of a preferred antibiotic for empiric therapy depending on the infection location and whether the source of the disease is nosocomial or community-acquired.

Effects of concentration of corn distillers dried grains with solubles and enzyme supplementation on cecal microbiota and performance in broiler chickens

With the increasing production of ethanol for biofuels, a by-product of corn-based ethanol fermentation, dried distillers grains with solubles (DDGS) is finding its way into the feed of agricultural animals including cattle, pigs, poultry, sheep, goats, aquaculture species and horses. Corn DDGS contains very high levels of non-starch polysaccharides and could be considered a good source of fibre. Despite knowledge of the role of the fibre in modulating intestinal microbiota and consequently influencing health, there is currently little information on the interactions between DDGS and intestinal microbiota. We assessed the changes in the cecal microbiota of broilers feed rations supplemented with DDGS (five concentrations: 0, 6, 12, 18 and 24% w/w) with and without presence of digestive enzymes. DDGS concentration was strongly positively correlated (P = 3.7e^-17, r = 0.74) with feed conversion efficiency (FCR), diminishing broiler performance with higher concentrations. Additionally, DDGS concentrations positively correlated with Richness index (P = 1.5e^-3, r = 0.5), increasing the number of detectable species in the cecum. Among the most affected genera, Faecalibacterium (P = 0.032, r = -0.34) and Streptococcus (P = 7.9e^-3, r = -0.39) were negatively correlated with DDGS, while Turicibacter (P = 2.8e^-4, r = 0.52) was positively correlated with the DDGS concentration. Enzymes showed minimal effect on cecal microbiota.

Intestinal microbiome in children with severe and complicated acute viral gastroenteritis

The aim of the present study was to evaluate the microbiota of children with severe or complicated acute viral gastroenteritis (AGE). To that end, next-generation sequencing (NGS) technology was used to sequence the 16S ribosomal RNA (16S rRNA) gene in 20 hospitalized pediatric patients with severe or complicated AGE and a further 20 otherwise healthy children; the fecal microbiome was then assessed. Comparative metagenomics data were analyzed by a Wilcoxon rank–sum test and hierarchical clustering analysis of bacterial reads. The statistical analyses showed a significantly decreased Shannon diversity index (entropy score) of the intestinal microbiota in patients with severe AGE compared with normal controls (P = 0.017) and patients with mild-to-moderate AGE (P = 0.011). The intestinal microbiota score of the 5 patients with rotavirus AGE was significantly lower than that of those with norovirus infection (P = 0.048). Greater richness in Campylobacteraceae (P = 0.0003), Neisseriaceae (P = 0.0115), Methylobacteriaceae (P = 0.0004), Sphingomonadaceae (P = 0.0221), and Enterobacteriaceae (P = 0.0451) was found in patients with complicated AGE compared with normal controls. The data suggest a significant reduction in intestinal microbial diversity in patients with severe AGE, particularly those with rotavirus infection.

Transovarial Transmission of Symbionts in Insects

Many insects, on account of their unbalanced diet, live in obligate symbiotic associations with microorganisms (bacteria or yeast-like symbionts), which provide them with substances missing in the food they consume. In the body of host insect, symbiotic microorganisms may occur intracellularly (e.g., in specialized cells of mesodermal origin termed bacteriocytes, in fat body cells, in midgut epithelium) or extracellularly (e.g., in hemolymph, in midgut lumen). As a rule, symbionts are vertically transmitted to the next generation. In most insects, symbiotic microorganisms are transferred from mother to offspring transovarially within female germ cells. The results of numerous ultrastructural and molecular studies on symbiotic systems in different groups of insects have shown that they have a large diversity of symbiotic microorganisms and different strategies of their transmission from one generation to the next. This chapter reviews the modes of transovarial transmission of symbionts between generations in insects.

Gut-lung axis: The microbial contributions and clinical implications

Gut microbiota interacts with host immune system in ways that influence the development of disease. Advances in respiratory immune system also broaden our knowledge of the interaction between host and microbiome in the lung. Increasing evidence indicated the intimate relationship between the gastrointestinal tract and respiratory tract. Exacerbations of chronic gut and lung disease have been shown to share key conceptual features with the disorder and dysregulation of the microbial ecosystem. In this review, we discuss the impact of gut and lung microbiota on disease exacerbation and progression, and the recent understanding of the immunological link between the gut and the lung, the gut-lung axis.

Gut Microbiota Promote Angiotensin II-Induced Arterial Hypertension and Vascular Dysfunction

Background

The gut microbiome is essential for physiological host responses and development of immune functions. The impact of gut microbiota on blood pressure and systemic vascular function, processes that are determined by immune cell function, is unknown.

Methods and Results

Unchallenged germ‐free mice (GF) had a dampened systemic T helper cell type 1 skewing compared to conventionally raised (CONV‐R) mice. Colonization of GF mice with regular gut microbiota induced lymphoid mRNA transcription of T‐box expression in T cells and resulted in mild endothelial dysfunction. Compared to CONV‐R mice, angiotensin II (AngII; 1 mg/kg per day for 7 days) infused GF mice showed reduced reactive oxygen species formation in the vasculature, attenuated vascular mRNA expression of monocyte chemoattractant protein 1 (MCP‐1), inducible nitric oxide synthase (iNOS) and NADPH oxidase subunit Nox2, as well as a reduced upregulation of retinoic‐acid receptor‐related orphan receptor gamma t (Rorγt), the signature transcription factor for interleukin (IL)‐17 synthesis. This resulted in an attenuated vascular leukocyte adhesion, less infiltration of Ly6G⁺ neutrophils and Ly6C⁺ monocytes into the aortic vessel wall, protection from kidney inflammation, as well as endothelial dysfunction and attenuation of blood pressure increase in response to AngII. Importantly, cardiac inflammation, fibrosis and systolic dysfunction were attenuated in GF mice, indicating systemic protection from cardiovascular inflammatory stress induced by AngII.

Conclusion

Gut microbiota facilitate AngII‐induced vascular dysfunction and hypertension, at least in part, by supporting an MCP‐1/IL‐17 driven vascular immune cell infiltration and inflammation.

The Gut-Brain Axis, BDNF, NMDA and CNS Disorders

Gastro-intestinal (GI) microbiota and the 'gut-brain axis' are proving to be increasingly relevant to early brain development and the emergence of psychiatric disorders. This review focuses on the influence of the GI tract on Brain-Derived Neurotrophic Factor (BDNF) and its relationship with receptors for N-methyl-D-aspartate (NMDAR), as these are believed to be involved in synaptic plasticity and cognitive function. NMDAR may be associated with the development of schizophrenia and a range of other psychopathologies including neurodegenerative disorders, depression and dementias. An analysis of the routes and mechanisms by which the GI microbiota contribute to the pathophysiology of BDNF-induced NMDAR dysfunction could yield new insights relevant to developing novel therapeutics for schizophrenia and related disorders. In the absence of GI microbes, central BDNF levels are reduced and this inhibits the maintenance of NMDAR production. A reduction of NMDAR input onto GABA inhibitory interneurons causes disinhibition of glutamatergic output which disrupts the central signal-to-noise ratio and leads to aberrant synaptic behaviour and cognitive deficits. Gut microbiota can modulate BDNF function in the CNS, via changes in neurotransmitter function by affecting modulatory mechanisms such as the kynurenine pathway, or by changes in the availability and actions of short chain fatty acids (SCFAs) in the brain. Interrupting these cycles by inducing changes in the gut microbiota using probiotics, prebiotics or antimicrobial drugs has been found promising as a preventative or therapeutic measure to counteract behavioural deficits and these may be useful to supplement the actions of drugs in the treatment of CNS disorders.

Linking Smoking, Coffee, Urate, and Parkinson's Disease - A Role for Gut Microbiota?

While the etiology and pathogenesis of Parkinson's disease (PD) is still obscure, there is evidence for lifestyle factors influencing disease risk. Best established are the inverse associations with smoking and coffee consumption. In other contexts there is evidence that health effects of lifestyle factors may depend on gut microbiome composition. Considering the gastrointestinal involvement in PD, it was recently speculated, that the associations between smoking, coffee, and PD risk could be mediated by gut microbiota. Here we review such a possible mediatory role of gut microbiota taking into account recent findings on microbiome composition in PD and extending the scope also to urate.

Lactobacillus plantarum NCIMB8826 ameliorates inflammation of colon and skin in human APOC1 transgenic mice

Genetic predisposition and environmental factors, including the gut microbiota, have been suggested as major factors in the development and progression of atopic dermatitis. Hyperlipidemic human APOC1+/+ transgenic mice display many features of human atopic dermatitis, such as scaling, lichenification, excoriations, and pruritus, along with a disturbed skin barrier function. Cytokine analysis of serum shows an increase of various pro-inflammatory cytokines, including interleukin (IL)-12p40, IL-6, and IL-1α, but lower levels of interferon-γ. These mice also display aspects of colitis evident from macroscopic and histological abnormalities. Genome-wide transcriptome analysis of the intestine shows up-regulation of several genes associated with mast cells and eosinophils and this observation was confirmed by demonstrating increased numbers of IgE+ and FcRε+ mast cells in the colon and in the skin. Oral treatment with Lactobacillus plantarum NCIMB8826 resulted in decreased numbers of mast cells in the colon. Moreover, this L. plantarum strain ameliorated skin pathology, evident from improved skin barrier integrity, absence of skin thickening, and less excoriations. These results suggest that modulation of intestinal immune homeostasis contributes to the suppression of atopic dermatitis.

Viruses in Rodent Colonies: Lessons Learned from Murine Noroviruses

Noroviruses (NoVs) are highly prevalent, positive-sense RNA viruses that infect a range of mammals, including humans and mice. Murine noroviruses (MuNoVs) are the most prevalent pathogens in biomedical research colonies, and they have been used extensively as a model system for human noroviruses (HuNoVs). Despite recent successes in culturing HuNoVs in the laboratory and a small animal host, studies of human viruses have inherent limitations. Thus, owing to its versatility, the MuNoV system-with its native host, reverse genetics, and cell culture systems-will continue to provide important insights into NoV and enteric virus biology. In the current review, we summarize recent findings from MuNoVs that increase our understanding of enteric virus pathogenesis and highlight similarities between human and murine NoVs that underscore the value of MuNoVs to inform studies of HuNoV biology. We also discuss the potential of endemic MuNoV infections to impact other disease models.

Burkholderia gut symbionts enhance the innate immunity of host Riptortus pedestris

The relation between gut symbiosis and immunity has been reported in various animal model studies. Here, we corroborate the effect of gut symbiont to host immunity using the bean bug model. The bean bug, Riptortus pedestris, is a useful gut symbiosis model due to the monospecific gut symbiont, genus Burkholderia. To examine the effect of gut symbiosis to host immunity, we generated the gut symbiont-harboring (symbiotic) insect line and the gut symbiont-lacking (aposymbiotic) insect line. Upon bacterial challenges, the symbiotic Riptortus exhibited better survival than aposymbiotic Riptortus. When cellular immunity was inhibited, the symbiotic Riptortus still survived better than aposymbioic Riptortus, suggesting stronger humoral immunity. The molecular basis of the strong humoral immunity was further confirmed by the increase of hemolymph antimicrobial activity and antimicrobial peptide expression in the symbiotic insects. Taken together, our data clearly demonstrate that Burkhoderia gut symbiont positively affect the Riptortus systemic immunity.

Microbiome and Asthma: What Have Experimental Models Already Taught Us?

Asthma is a chronic inflammatory disease that imposes a substantial burden on patients, their families, and the community. Although many aspects of the pathogenesis of classical allergic asthma are well known by the scientific community, other points are not yet understood. Experimental asthma models, particularly murine models, have been used for over 100 years in order to better understand the immunopathology of asthma. It has been shown that human microbiome is an important component in the development of the immune system. Furthermore, the occurrence of many inflammatory diseases is influenced by the presence of microbes. Again, experimental models of asthma have helped researchers to understand the relationship between the microbiome and respiratory inflammation. In this review, we discuss the evolution of murine models of asthma and approach the major studies involving the microbiome and asthma.

The Interaction among Microbiota, Immunity, and Genetic and Dietary Factors Is the Condicio Sine Qua Non Celiac Disease Can Develop

Celiac disease (CD) is an immune-mediated enteropathy, triggered by dietary wheat gluten and similar proteins of barley and rye in genetically susceptible individuals. This is a complex disorder involving both environmental and immune-genetic factors. The major genetic risk factor for CD is determined by HLA-DQ genes. Dysfunction of the innate and adaptive immune systems can conceivably cause impairment of mucosal barrier function and development of localized or systemic inflammatory and autoimmune processes. Exposure to gluten is the main environmental trigger responsible for the signs and symptoms of the disease, but exposure to gluten does not fully explain the manifestation of CD. Thus, both genetic determination and environmental exposure to gluten are necessary for the full manifestation of CD; neither of them is sufficient alone. Epidemiological and clinical data suggest that other environmental factors, including infections, alterations in the intestinal microbiota composition, and early feeding practices, might also play a role in disease development. Thus, this interaction is the condicio sine qua non celiac disease can develop. The breakdown of the interaction among microbiota, innate immunity, and genetic and dietary factors leads to disruption of homeostasis and inflammation; and tissue damage occurs. Focusing attention on this interaction and its breakdown may allow a better understanding of the CD pathogenesis and lead to novel translational avenues for preventing and treating this widespread disease.

Stress-activated Dendritic Cells (DC) Induce Dual Interleukin (IL)-15- and IL1β-mediated Pathways, Which May Elicit CD4+ Memory T Cells and Interferon (IFN)-stimulated Genes

The prevailing evidence suggests that immunological memory does not require antigenic re-stimulation but is maintained by low level tonic stimulation. We examined the hypothesis that stress agents contribute to tonic cellular activation and maintain immunological memory. Stimulation of monocyte-derived dendritic cells (DC) with stress agents elicits reactive oxygen species and HSP70. NFκB is activated, which up-regulates membrane-associated (ma) IL-15, caspase-1 and IL-1β. Co-culture of stress-treated DC with mononuclear cells activates IL-15 and IL-1β receptors on CD4(+) T cells, eliciting CD40L, proliferation, and up-regulation of CD45RO(+) memory T cells. The transcription factors Tbet(high) and RORγt are up-regulated, whereas FoxP3 is down-regulated, resulting in enhanced Th1 and Th17 expression and the corresponding cytokines. The interaction between maIL-15 expressed by DC and IL-15R on CD4(+) T cells results in one pathway and the corresponding cells expressing IL-1β and IL1βR as a second pathway. Importantly, inhibition studies with IL-15 antibodies and IL-1βR inhibitor suggest that both pathways may be required for optimum CD4(+) CD45RO(+) memory T cell expression. Type 1 IFN expression in splenic CD11c DC of stress-treated mice demonstrated a significant increase of IFN-α in CD11c CD317(+) and CD8α(+) DC. Analysis of RNA in human CD4(+) memory T cells showed up-regulation of type 1 IFN-stimulated genes and inhibition with histone methyltransferase inhibitor. We suggest the paradigm that stress-induced tonic stimulation might be responsible for the robust persistence of the immune response in vaccination and that epigenetic changes are involved in maintaining CD4(+) T cell memory.

Contributing factors to the development of childhood asthma: working toward risk minimization

Asthma is the most common chronic disease in childhood, and considerable research has been undertaken to find ways to prevent its development and reduce its prevalence. For such interventions to be successful, risk factors for asthma emergence should be identified and clearly defined. Data are robust for some of them, including atopy, viral infections and exposure to airborne irritants, whereas it is less conclusive for others, such as aeroallergen exposure and bacterial infections. Several interventions for asthma prevention, including avoidance and pharmacotherapy, have been attempted. However, most of them have furnished equivocal results. Various issues hinder the establishment of risk factors for asthma development and reduce the effectiveness of interventions, including the complexity of the disease and the fluidity of the developing systems in childhood. In this review, we revisit the evidence on pediatric asthma risk factors and prevention and discuss issues that perplex this field.

Is there a role for probiotics in liver disease?

Intestinal microbiota plays an important role in health and disease. Alteration in its healthy homeostasis may result in the development of numerous liver disorders including complications of liver cirrhosis. On the other hand, restoration and modulation of intestinal flora through the use of probiotics is potentially an emerging therapeutic strategy. There is mounting evidence that probiotics are effective in the treatment of covert and overt hepatic encephalopathy, as well as in the prevention of recurrence of encephalopathy. The beneficial effect of probiotics also extends to liver function in cirrhosis, nonalcoholic fatty liver disease, and alcoholic liver disease. On the other hand, data associating probiotics and portal hypertension is scanty and conflicting. Probiotic therapy has also not been shown to prevent primary or secondary spontaneous bacterial peritonitis. Larger clinical studies are required before probiotics can be recommended as a treatment modality in liver diseases.

An intestinal commensal symbiosis factor controls neuroinflammation via TLR2-mediated CD39 signalling

The mammalian immune system constitutively senses vast quantities of commensal bacteria and their products through pattern recognition receptors, yet excessive immune reactivity is prevented under homeostasis. The intestinal microbiome can influence host susceptibility to extra-intestinal autoimmune disorders. Here we report that polysaccharide A (PSA), a symbiosis factor for the human intestinal commensal Bacteroides fragilis, protects against central nervous system demyelination and inflammation during experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, through Toll-like receptor 2 (TLR2). TLR2 mediates tissue-specific expansion of a critical regulatory CD39(+) CD4 T-cell subset by PSA. Ablation of CD39 signalling abrogates PSA control of EAE manifestations and inflammatory cytokine responses. Further, CD39 confers immune-regulatory phenotypes to total CD4 T cells and Foxp3(+) CD4 Tregs. Importantly, CD39-deficient CD4 T cells show an enhanced capability to drive EAE progression. Our results demonstrate the therapeutic potential and underlying mechanism by which an intestinal symbiont product modulates CNS-targeted demyelination.

The effect of malnutrition on norovirus infection

Human noroviruses are the primary cause of severe childhood diarrhea in the United States, and they are of particular clinical importance in pediatric populations in the developing world. A major contributing factor to the general increased severity of infectious diseases in these regions is malnutrition-nutritional status shapes host immune responses and the composition of the host intestinal microbiota, both of which can influence the outcome of pathogenic infections. In terms of enteric norovirus infections, mucosal immunity and intestinal microbes are likely to contribute to the infection outcome in substantial ways. We probed these interactions using a murine model of malnutrition and murine norovirus infection. Our results reveal that malnutrition is associated with more severe norovirus infections as defined by weight loss, impaired control of norovirus infections, reduced antiviral antibody responses, loss of protective immunity, and enhanced viral evolution. Moreover, the microbiota is dramatically altered by malnutrition. Interestingly, murine norovirus infection also causes changes in the host microbial composition within the intestine but only in healthy mice. In fact, the infection-associated microbiota resembles the malnutrition-associated microbiota. Collectively, these findings represent an extensive characterization of a new malnutrition model of norovirus infection that will ultimately facilitate elucidation of the nutritionally regulated host parameters that predispose to more severe infections and impaired memory immune responses. In a broad sense, this model may provide insight into the reduced efficacy of oral vaccines in malnourished hosts and the potential for malnourished individuals to act as reservoirs of emergent virus strains. IMPORTANCE Malnourished children in developing countries are susceptible to more severe infections than their healthy counterparts, in particular enteric infections that cause diarrhea. In order to probe the effects of malnutrition on an enteric infection in a well-controlled system devoid of other environmental and genetic variability, we studied norovirus infection in a mouse model. We have revealed that malnourished mice develop more severe norovirus infections and they fail to mount effective memory immunity to a secondary challenge. This is of particular importance because malnourished children generally mount less effective immune responses to oral vaccines, and we can now use our new model system to probe the immunological basis of this impairment. We have also determined that noroviruses evolve more readily in the face of malnutrition. Finally, both norovirus infection and malnutrition independently alter the composition of the intestinal microbiota in substantial and overlapping ways.

Asthma microbiome studies and the potential for new therapeutic strategies

Recent applications of culture-independent tools for microbiome profiling have revealed significant relationships between asthma and microbiota associated with the environment, gut, or airways. Studies of the airway microbiome in particular represent a new frontier in pulmonary research. Although these studies are relatively new, current evidence suggests the possibility of new therapeutic strategies for the treatment or prevention of asthma. In this article, recent literature on microbiota and asthma are critically reviewed, with a particular focus on studies of the airway microbiome. Perspectives are presented on how growing knowledge of relationships between the microbiome and asthma is likely to translate into improved understanding of asthma pathogenesis, its heterogeneity, and opportunities for novel treatment approaches.

Role of gut microbiota in pathogenesis of nonalcoholic fatty liver disease

A close anatomical and functional interplay exists between the gut and liver, named "gut-liver axis", which has been associated with the pathogenesis of some diseases. Intestinal bacteria play a key role in the maintenance of gut-liver axis health. Altered intestinal bacterial flora, increased intestinal permeability and gut-associated endotoxemia will damage the normal relationship between the liver and intestine, which in turn leads to a variety of liver disease. Thus, modulation of the gut microbiota may represent a new way to treat or prevent chronic liver disease. Studies have showed that gut microflora plays a significant role in the development of nonalcoholic fatty liver disease. This review summarizes the recent studies highlighting the role of the intestinal microflora in the development of NAFLD.

Commensal microbiota stimulate systemic neutrophil migration through induction of serum amyloid A

Neutrophils serve critical roles in inflammatory responses to infection and injury, and mechanisms governing their activity represent attractive targets for controlling inflammation. The commensal microbiota is known to regulate the activity of neutrophils and other leucocytes in the intestine, but the systemic impact of the microbiota on neutrophils remains unknown. Here we utilized in vivo imaging in gnotobiotic zebrafish to reveal diverse effects of microbiota colonization on systemic neutrophil development and function. The presence of a microbiota resulted in increased neutrophil number and myeloperoxidase expression, and altered neutrophil localization and migratory behaviours. These effects of the microbiota on neutrophil homeostasis were accompanied by an increased recruitment of neutrophils to injury. Genetic analysis identified the microbiota-induced acute phase protein serum amyloid A (Saa) as a host factor mediating microbial stimulation of tissue-specific neutrophil migratory behaviours. In vitro studies revealed that zebrafish cells respond to Saa exposure by activating NF-κB, and that Saa-dependent neutrophil migration requires NF-κB-dependent gene expression. These results implicate the commensal microbiota as an important environmental factor regulating diverse aspects of systemic neutrophil development and function, and reveal a critical role for a Saa-NF-κB signalling axis in mediating neutrophil migratory responses.

Recognition of gut microbiota by NOD2 is essential for the homeostasis of intestinal intraepithelial lymphocytes

NOD2 signaling maintains intestinal intraepithelial lymphocytes via recognition of gut microbiota and IL-15 production.

NOD2 functions as an intracellular sensor for microbial pathogen and plays an important role in epithelial defense. The loss-of-function mutation of NOD2 is strongly associated with human Crohn’s disease (CD). However, the mechanisms of how NOD2 maintains the intestinal homeostasis and regulates the susceptibility of CD are still unclear. Here we found that the numbers of intestinal intraepithelial lymphocytes (IELs) were reduced significantly in Nod2^−/− mice and the residual IELs displayed reduced proliferation and increased apoptosis. Further study showed that NOD2 signaling maintained IELs via recognition of gut microbiota and IL-15 production. Notably, recovery of IELs by adoptive transfer could reduce the susceptibility of Nod2^−/− mice to the 2,4,6-trinitrobenzene sulfonic acid (TNBS)–induced colitis. Our results demonstrate that recognition of gut microbiota by NOD2 is important to maintain the homeostasis of IELs and provide a clue that may link NOD2 variation to the impaired innate immunity and higher susceptibility in CD.